1. Field of the Invention
The present invention relates to a high-speed rotation testing apparatus, and in particular, to a high-speed rotation testing apparatus preferably used to achieve processing of test objects stored in the rotor in a high gravitational acceleration field using centrifugal force generated by rotating a rotor at high speed.
2. Description of the Related Art
Conventionally, apparatuses have been under development for enabling generation of an extremely large gravitational acceleration field so as to achieve, by an external force, highly condensed sedimentation diffusion of atoms or molecules of condensed substances formed of two or more elements. A high-speed rotation testing apparatus as shown in FIG. 9 is known to those skilled in the art, and is used for generating a high gravitational acceleration field using centrifugal force by rotating a rotor at high speed. The apparatus will be described.
As shown in FIG. 9, the apparatus comprises a combustor (not shown), an air turbine motor 101 and a rotor 102 for storing a test object container. Combustion gas from the combustor is introduced to the air turbine motor 101 as represented by an arrow A in FIG. 9, and the rotation torque is applied to a rotor shaft 103. The rotor shaft 103 is supported by an oil float bearing 104 and a stator bushing 105. The rotor 102 is secured to the tip of the rotor shaft 103.
Next, the shape of the rotor 102 will be described by referring to FIG. 10. FIG. 10A shows a fragmentary sectional view of the rotor 102 as viewed from the front while FIG. 10B shows the view from the bottom. The rotor 102 has a shape of a cone with the tip being cut off, that is, a substantial conic trapezoid. A shaft hole 102a is formed in the rotor 102 so that the rotor shaft 103 is inserted into the center of the circle, the end faces of the rotor 102. By inserting the rotor shaft 103 to the shaft hole 102a and securing a nut 106 to the tip of the rotor shaft 103, the rotor 102 is interposed between the nut 106 and the stator bushing 105 thereby to be fixed to the tip of the rotor shaft 103. Also, on one end face of the rotor 102, that is, the face of the rotor shaft 103 on the tip side, hollows 107a and 107b for test objects with a predetermined depth are formed along a ridgeline arranged towards the other end face (air turbine motor side). A condensed substance M as the test object is stored in the hollows 107a and 107b and then the rotor 102 is rotated at high speed. Thereby, the test object can be processed under large gravitational acceleration by the centrifugal force.
Specifically, with the high-speed rotation testing apparatus, an acceleration field more than 200,000 gravitation acceleration (in the followings, referred to as xe2x80x9cgxe2x80x9d) can be generated at the temperatures over 60xc2x0 C. In general, the acceleration field xcex1 is represented by xcex1=rxcfx892 provided that the angular velocity around the rotor shaft is xcfx89, and the length of the perpendicular from an object to the rotor shaft is r. The required rotating speed varies according to the size of the inner radius r of the test object container. For example, in the case where the inner radius r of the test object container is 20 mm, it is necessary to achieve high-speed rotation with the maximum rotating speed of 200,000 rpm or more in order to generate 810,000 g of gravitational acceleration.
However, there are problems as described below with the high-speed rotation testing apparatus in the example of the related art.
First, there is a shaft hole provided in the rotational center of the above-described rotor. Thus, the shaft hole cannot endure the stress at the time of high-speed rotation due to a high-gravitational acceleration field, which may result in deformation or the like of the rotor. Therefore, it is necessary to limit the rotating speed of the rotor to a predetermined value.
Also, the atmosphere surrounding the rotor is in the atmospheric air so that there is a frictional resistance generated by windage, which leads to a problem that the rotating speed is suppressed by the resistance. If the frictional resistance by windage is suppressed through decompressing the atmosphere surrounding the rotor, the resistance on the rotor is reduced so that the rotating speed can be increased. However, in this case, heat transfer via the air cannot be utilized so that the heating/cooling efficiency of the rotor is deteriorated. Therefore, it is difficult to control the temperature of the test object and the test contents of the test object are to be limited.
Further, by supporting the rotation shaft by the stator bushing, the relative speed of the rotation shaft and the bushing is increased, thereby causing seizure due to the friction generated therebetween. Hence, it is difficult to continue high-speed rotation of the rotor for a long time.
The present invention has been designed to overcome the foregoing problems. Specifically, an object of the invention is to provide a high-speed rotation testing apparatus which can achieve more high-speed rotation of a rotor to which a test object is stored and can extend the duration of high-speed rotation while enabling the control of the temperature of the rotor at the time of high-speed rotation.
A high-speed rotation testing apparatus according to present invention, comprising: a rotor having a hollow for a test object for storing a predetermined test object; a spindle whose one end portion is connected to a rotation center of said rotor; a torque applying device connected to the other end portion of said spindle for applying a predetermined torque to said spindle; and a casing for storing said rotor by sealing, wherein said casing comprises a decompressing device for decompressing atmospheric pressure inside said casing and a holder for holding said spindle by inserting through said spindle, wherein said holder comprises at least one bushing for supporting said spindle and a bushing supporting member for supporting said bushing by inserting therethrough, wherein an inner diameter of said at least one bushing supporting member is formed larger than an outer diameter of said bushing to be inserted into said bushing supporting member so that said bushing supporting member supports said bushing to be rotatable.
With the configuration, torque applied from the torque applying device to the spindle transmits to the rotor so that the rotor rotates at a high speed under decompressed atmosphere. At this time, the spindle is supported by the bushing provided inside the supporting means. Thus, due to the friction between the spindle and the bushing, torque is applied so that the bushing is also rotated in the same direction as the rotating direction of the spindle. The bushing is supported by a bushing supporting member with a predetermined clearance in between so that the bushing is rotatable against the bushing supporting member. Hence, when the bushing is fixed to the bushing supporting member, the relative rotating speeds of the bushing and the bushing supporting member is suppressed. Thus, the friction generated between the members can be reduced thereby preventing generation of seizure. As a result, more high-speed rotation of the rotor can be achieved and, at the same time, it becomes possible to maintain high-speed rotation for a long time.
And said bushing which is rotatably supported by said predetermined bushing supporting member may be provided only on said torque applying device side of said holder. In other words, the bushing provided in the spindle on the rotor side may be supported by being fixed to the bushing supporting member. Thereby, the spindle is stably supported near the rotor. Thus, swing of the spindle can be suppressed and stable high-speed rotation of the rotor can be achieved. At the same time, friction generated between the spindle and the bushing can be suppressed on the torque applying device side. Therefore, high-speed rotation of the rotor can be achieved for a long time as in the case described earlier.
Moreover, in a rotation center of said rotor, it is preferably a spindle connecting portion projected from said rotor towards said torque applying device side is formed for connecting to said spindle. And, in the projected end of said spindle connecting portion, a shaft hole for inserting and connecting said spindle is formed while providing a depth of the shaft hole not to be inserted into said spindle connecting portion.
Thereby, the spindle connecting portion for connecting the spindle is formed being projected from the rotational center of the rotor. In other words, the spindle connecting portion is formed as one body with the rotor. Since the spindle is connected by inserting into the shaft hole formed in a predetermined depth from the projection end of the spindle connecting portion, it becomes unnecessary to form a shaft hole in the rotational center of the rotor inserting through the spindle connecting portion and the rotor main body. Therefore, such a problem including deformation of the shape of the rotor or the like due to unbearable stress of the centrifugal force by the high-speed rotation imposed on the through-hole can be suppressed, which may otherwise occur in the case with a through-hole in the rotor as a shaft hole. In other words, the state of the rotor such as the shape of the rotor at the time of high-speed rotation can be stabilized so that more high-speed rotation can be achieved.
Conventionally, an air turbine driven by combustion gas is used as a torque applying device. However, it is preferably the torque applying device is an air turbine which is rotationally driven by a supply of compressed air or an electric driving motor. Thereby, it becomes unnecessary to use a combustor which generates a combustion gas. Thus, unlike the related art, transmission of the heat from the combustor to the test object stored in the rotor can be avoided. As a result, increase in the temperature of the rotor at the time of high-speed rotation, that is, increase in the temperature of the test object can be prevented. Hence, the temperature control of the test object can be achieved.
Moreover, in the vicinity of said rotor inside said casing, a radiation member with a predetermined area is provided and, at the same time, a radiation temperature controller for controlling temperatures of said radiation member is provided. It is more preferably said radiation member is formed in annular shape so as to surround a rotation periphery of said rotor. By heating/cooling the radiation member using the temperature controller, radiation heat is generated in the rotor by the radiation from the radiation member. Thereby, the rotor can be heated or cooled. At this time, the rotor can be effectively heated/cooled by providing the radiation member in an annular form to surround the rotor. Thereby, even if the rotor is in the decompressed atmosphere, the temperature of the rotor can be controlled so that the processing temperature of the test object can be set.